As is known in the art, distributed storage systems, such as Elastic Cloud Storage (ECS) from EMC Corporation of Hopkinton, Mass., provide a wide range of storage services. Some distributed storage systems (e.g., ECS) manage storage capacity by partitioning storage devices into fixed-size blocks referred to as “storage chunks” or “chunks.” Various types of information, including user data, system data, and metadata, may be stored in chunks.
Various users and system processes may allocate storage chunks. Over time, the number of allocated chunks—and, thus, used storage capacity—tends to increase. Even operations to delete user data may require allocating new storage chunks. Likewise, system processes that reclaim unused storage chunks (e.g., garbage collection) may allocate storage chunks.
Without proper controls, it is possible to end up in a situation when no new storage chunks can be allocated due to lack of free storage space (e.g., disk space). There may be no way to recover from this situation because deleting user data and reclaiming unused capacity both require allocating new storage chunks.